Lever escapement



Jan. 14, 1958 F. MART! ETAL LEVER ESCAPEMENT Filed Aug. 19, 1954 3YlllL.

f iQ

VENTORS FRITZ MARTI GEORGES BRAUNSCHWEIG Attorneys United States Patent muvnnnsounmm Fritz Marti and Georges Braunschwei'g,

rLa Qirauxde-Eonds, Switzerhnd x licmonmi ustaigrasrt, Serial *No. 450,868

priority, applicationSwitzerland Auguist'22, 1953 3 Claims. c1. 58-121) This invention relates to lever escapements of time pieces.

The problem of lubrication of the operative surfaces of the lever escapements has always met with some technical difficulties and numerous solutions have been suggested or brought into practice. For instance, oil cups in the shape of recesses, grooves or holes have been provided either in the teeth of the escape wheel or in the jewels or pins of the pallet in order to avoid stagnation of the oil drop in the corner formed by the back side of the tooth and the rim of the escape wheel and to bring back as much as possible the oil to the rest plane of the tooth. However none of the arrangements previously suggested has brought a complete solution to this problem. It has been proved by experience that if on the one hand the co-operation of the pallet jewels with the teeth of the escape wheel tends to activate the oil circulation, on the other hand the oil transferred tends always to escape from the circuit, either along the jewel or along the sides of the tooth towards the rim of the escape wheel.

It is accordingly primarily within the contemplation of our invention to eliminate the aforesaid shortcomings in devices of the above mentioned category by providing means to ensure constant, effective and durable lubrication of the operatively associated surfaces of the lever escapements.

It is an object of our invention to provide means on both the teeth of the escape wheel and on the jewels of the pallet to create by capillarity two distinct and conjugate oil circuits, the first one between the rest plane and the impulse plane of the pallet jewels, the other one between the impulse plane and the rest plane of each tooth of the escape wheel.

In order to create by capillarity a continuous travel of the oil around the jewel, the collar or groove means must be provided in close vicinity of the free end of the jewel, and on at least three sides thereof, that is to say the capillary path must be uninterrupted.

However, provision of an uninterrupted capillary path around the jewel or around the tooth of the escape wheel will not be sufficient to keep constant lubrication of the cooperating surfaces, for if only one of the cooperating members (tooth or jewel) is provided with such a path, the oil will tend to escape toward the center of the wheel or toward the pivot of the anchor. It has been proved by experience that all the known constructions which provide oil recesses merely in one of the members of the escapement are ineffective in that after a little while there is no more oil in the recess.

Referring to the drawings:

Figure 1 is a fragmetnary plan view of a lever escapement showing the main combination of components constituting our invention.

Figure 2 is a plan view on enlarged scale of a tooth of the escape wheel.

.rno'dified form :of pallet jewel, and

Figure 8 is a section on line VIII- Vlll' of Figure 7. In the form of our invention illustratedin' theFrgures l' to 5, a constructioniof lever escapement'is'shown which comprises an escape'wheel'rand a jewelld'pallet l, the jewels5 an'd6 of which "co-operatewith the 'teethl of the wheel. On the lower or upper face of each tooth 2 there is provided, close to the plane of impulse 2b, a rectilinear groove 3 extending from the back side 20, to the rest plane 2a. This groove whose cross section may assume any shape whatever, forms an acute angle with the impulse plane 2b. It could of course extend parallelly to this plane or in a curved line, for instance, concentrically to the rim of the escape wheel.

On the other hand, each jewel 5 and 6 of the pallet 4 is provided with a collarette 7 force-fitted over its free end and held in place by means of a small notch 8 provided in one of the sides of the jewel. The collarette 7 can be constituted by a thin concave washer of glucinium bronze or stainless steel, which can be force-fitted over the jewel by curving it a little more until one side thereof enters the notch 8.

The collarette shown in Figure 6 is a U-shaped thin metallic blade open at one side and secured by means of two notches 10 and 11 provided on two opposite sides of the pallet jewel 12.

It is to be understood that the co-operative association of the groove 3 in the tooth 2 of the escape wheel with the collarette 7 or 9 on the jewels 5, 6, 12, 13 permits, owing to the capillarity, to create two distinct oil circuits with conjugate action, to wit, a first circuit around the jewel of the pallet, and a second circuit around the tooth of the escape wheel, thus resulting in the oil being brought back integrally after each impulse to its starting point.

In the construction according to my invention, if an oil drop is taken at each impulse by the plane of impulse 2b of the tooth (Figure 2), it will be transferred by this plane and after the tooth has passed the back edge of the jewel, this drop is split in two portions, one of which flows back by the eifect of capillarity along the collar 7 and the other half, which is now below the back edge of the tooth, is brought again through the groove 3 towards the front edge of the plane 2b. There are, in fact, two distinct circuits tending to continuously bring back the oil drop to the back edge of the jewel and the front edge of the plane of impulse 2b.

It is apparent that the groove 3 will be advantageously provided as close as possible to the plane of impulse in order to facilitate the jewel in taking up the oil drop from the outer edge of the groove.

It is obvious that the relative position of the grooves and collarettes can be reversed, and that other means than those illustrated by way of example could be provided on the teeth of the escape wheel and on the jewels of the pallet to create two distinct and conjugate oil circuits. For instance the jewel 13 (Figs. 7 and 8) of the pallet could be provided with a groove 3 on three sides as illustrated in the Figures 7 and 8, whereas the teeth of the escape wheel could be provided either with another groove 3 or with a suitably shaped collarette.

Obviously many variations and modifications may be made in the invention which will still be comprised within its spirit. It is to be understood therefore, that the in vention is not limited to any specific form or manner of practicing same, except insofar as such limitations are specified in the appended claims.

We claim:

1. In a time-piece movement having a lever escapement, in combination an escape wheel and coactively associated therewith a pallet having two jewels mounted thereon to co-operate with the teeth of said escape wheel, a groove provided in at least one side of each tooth of said wheel and extending from the back side to the front side thereof, and a collar-shaped member mounted on the free end of each pallet jewel, whereby to create by capillarity two distinct and conjugate oil circuits around the tooth of the wheel and around the jewel.

2. In a time-piece movement having a lever escapement, the combination as claimed in claim 1 wherein the collar-shaped member is constituted by a thin metallic washer and wherein the jewel of the pallet is provided with a notch in at least one side surface thereof, said metallic washer being secured in said notch.

3. In a time-piece movement having a lever escapement, the combination as claimed in claim 1, wherein the collar-shaped member is constituted by a U-shaped metal blade and wherein the jewel is provided with two notches in opposite sides thereof said U-shaped metal blade being secured in said notches.

References Cited in the file of this patent UNITED STATES PATENTS 2,233,921 Iunghans Mar. 4, 1941 2,664,695 Huguenin Ian. 5, 1954 FOREIGN PATENTS 51,050 Germany Mat. 4, 1890 

